Continuous heating furnace



J. W. PERCY CONTINUOUS HEATING F'URNACE Filed Jan. ll, 1952 Sept. I14, 1954 IN V EN TOR.'

@E @EN N -n-m @urna Patented Sept. 14, 1954 CONTINUOUS HEATING FURNACE James W. Percy, Rutherford, N. J., assigner to United States Steel Corporation, a corporation of New Jersey Application January 11, 1952, Serial No', 266,046

1 Claim. 1

This invention relates to improvements in furnaces for continuous heating of articles such as billets, blooms, slabs orv the like.

An object of the invention is to provide a heating furnace which is highly flexible in its operation and efficient over widely varying operating rates.

A further object is to provide a heating furnace which has but two heating zones, thereby eliminating the complexities that arise in three zone furnaces, and which has an improved burner arrangement that promotes operating exibility and eiciency.

A more specic object is to provide a heating furnace which has a horizontal hearth and skids and two heating zones, one above the hearth and one below, and in which the zone above the hearth has a set of relatively large burners and a set of smaller burners, both of which sets are at the exit end and either or both of which can be fired at any time depending on the operating rate.

In accomplishing these and other objects of the invention, I have provided improved details of structure, preferred forms of which are shown in the accompanying drawing, in which:

Figure 1 is a vertical longitudinal sectional view of an improved furnace which embodies features of the present invention;

Figure 2 is an elevational view from the exit end taken substantially on line II-II of Figure l; and

Figure 3 is a fragmentary longitudinal sectional view of a modification.

Figures 1 and 2 show a continuous heating furnace which comprises side Walls II), a roof I2, a bottom I3, an entry end wall I4, and up-per and lower offset Walls I5 and I6 at the exit end.

. Within the enclosure formed by these walls there are the usual horizontal skid pipes Il, which occupy roughly 85 percent of the furnace length, and a hearth I8 which occupies the remainder of the length toward the exit end from said skids. The entry wall I 4 has an opening I9 through which articles S, such as billets, blooms or slabs, are introduced to the skids for heating in the usual way. After traveling the length of the skids and hearth, where they are heated to an appropriate temperature for hot Working, the articles are pushed from the furnace through an opening in one of the side walls, also in the usual way. Alternatively the articles can drop from a door 2I in the exit end Wall I5, as illustrated in Figure 3.

In accordance with the present invention, the

furnace has only two heating zones A and B, the former above the hearth and skids and the latter below the skids. Zone A is equipped with a row of main top burners 22 and a row of smaller auX- iliary burners 23 below said main burners. Both sets of burners 22 and 23 are in the upper wall I5 at the exit end. Zone B is equipped with a row of main bottom burners 24 in the lower Wall I6 at the exit end. The products of combustion from both zones discharge through lues 25 which open through the furnace roof I2 adjacent the entry end wall I4. The furnace is equipped with the usual recuperator 26, Which preferably is situated directly over the ues 25. Preferably the roof I2 has a raised section I2a adjacent the entry end of the furnace which helps to apply more heat to the cold articles as they are introduced, aids in recuperation and helps to prevent sting out at the entry opening I9.

In operation, the furnace can be red using either (a) the main bottom burners 24 and main top burners 22, (b) the main bottom burners 24 and auxiliary top burners 23, or (c) all three sets of burners. The first mode of firing is for normal rates of operation, the second for substantially lower rates, and the third for substantially higher rates. In addition the auxiliary burners 23 can be used as mill delay burners to hold the furnace at proper temperature during shut downs. Preferably the furnace has at least three temperature control points which are located as indicated at X in Figure land at which the usual automatic temperature controls are connected. Such an arrangement assures proper heating at any operata ing rate from a few tons per hours to more than tons per hour and automatically takes care of firing the furnace during mill delays.

I am aware that mill delay burners as such are known and also that two zone furnaces are known. Nevertheless, I believe it is novel to equip a two zone furnace with auxiliary burners which can be used either in conjunction with the other burners to regulate heating of the furnace or else as mill delay burners. Such a burner arrangement offers the advantage of operating iiexibility already referred to and in addition shortens the hearth length for a furnace of any given capacity.

While two embodiments of my invention have been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claim.

I claim:

A continuous heating furnace comprising side walls, a roof, a bottom, an entry end wall, an upper vertical wall at the exit end, a lower vertical wall at the exit end offset inwardly from said upper vertical Wall, said walls, roof and bottom forming an enclosure, horizontal skids supported in said enclosure and extending from said entry end wall to said lower vertical wall and spaced above said bottom, a horizontal hearth within said enclosure and extending from said lower vertical Wall to said upper vertical wall, the upper surface of said hearth being in the same horizontal plane as those of said skids, said side walls, roof, upper vertical wall, hearth and the upper surface of said skids dening a first heating zone, said side walls, bottom, lower vertical wall and the undersurface oi said skids defining a second heating zone, there being but two heating zones Within said enclosure, said enclosure having a discharge opening adjacent the exit end of said hearth, a row of main top burners located in the upper portion of said upper vertical Wall for supplying heat to said rst heating zone, a row of auxiliary top burners located in the lower portion of said upper vertical wall directly under said vmain top burners and disposed in relation to said hearth so as to supply heat to articles thereon immediately prior to their discharge through said discharge opening, and a row of main bottom burners in said lower vertical wall for supplying heat to said second heating zone, said enclosure having a flue opening adjacent the entry end in communication with both of said zones, said roof having a relatively high horizontal portion adjacent the exit end, a downwardly sloping portion extending from said horizontal portion toward the entry end, a relatively low horizontal portion extending from said sloping portion toward the entry end and forming a knuckle, and an upwardly sloping portion extending from said last named horizontal portion, said upwardly sloping portion defining with the other walls an expansion chamber beyond said knuckle, said flue Opening extending from said expansion chamber.

References Cited in the file of this patent UNITED STATES PATENTS 

